When you execute a realtime cache offer in Test mode, data is not posted to the RPI realtime cache.
When you do so in Production mode, the data output by the offer is stored as cached attributes in the realtime cache. If multiple data values are returned for an attribute, only one value is persisted in the cache. NULL values are not persisted in the cache. Any attributes that appear more than once in the offer are ignored. If an attribute already has a value in the cache, it is refreshed with the latest value.
The realtime cache channel's Key attribute is used as a lookup to a visitor's ID. If a visitor was identified at the time of the offer's execution, cached attribute values are merged into the existing visitor profile. If the visitor was not identified, cached attribute values are written to a new profile. This profile can be merged with a visitor's existing profile at the point of their being identified by RPI.
You can execute a realtime cache offer in a queue activity. When you do so in Production mode, data is posted to realtime cache, with the key being identified either using a parameter attribute with a name matching that of the realtime cache channel's Key attribute being contained within the JSON packet or using the packet's SendAddress property.
Note that, if a realtime cache offer is executed in a queue activity in in Test mode, data is posted to the realtime cache.
Note also that rolling back a production realtime cache offer workflow does not remove its data from the realtime cache.